Spread spectrum sensor scanning using resistive-inductive-capacitive sensors

ABSTRACT

A system may include at least one resistive-inductive-capacitive sensor and a control circuit configured to maintain timing parameters for operation of the at least one resistive-inductive-capacitive sensor and vary at least one of the timing parameters to control a spectrum associated with the at least one resistive-inductive-capacitive sensor, wherein the spectrum comprises one of a sensor activity spectrum of the at least one resistive-inductive-capacitive sensor and a current usage spectrum associated with electrical current delivered to the at least one resistive-inductive-capacitive sensor from a source of electrical energy.

RELATED APPLICATION

The present disclosure claims priority to U.S. Provisional PatentApplication Ser. No. 62/810,797, filed Feb. 26, 2019, which isincorporated by reference herein in its entirety.

The present disclosure relates to U.S. Provisional patent applicationSer. No. 16/267,079, filed Feb. 4, 2019, U.S. Provisional PatentApplication Ser. No. 62/649,857, filed Mar. 29, 2018, U.S. ProvisionalPatent Application Ser. No. 62/721,134, filed Aug. 22, 2018, and U.S.Provisional Patent Application Ser. No. 62/740,029, filed Oct. 2, 2018,all of which are incorporated by reference herein in their entireties.

FIELD OF DISCLOSURE

The present disclosure relates in general to electronic devices withuser interfaces, (e.g., mobile devices, game controllers, instrumentpanels, etc.), and more particularly, resonant phase sensing ofresistive-inductive-capacitive sensors for use in a system formechanical button replacement in a mobile device, and/or other suitableapplications.

BACKGROUND

Many traditional mobile devices (e.g., mobile phones, personal digitalassistants, video game controllers, etc.) include mechanical buttons toallow for interaction between a user of a mobile device and the mobiledevice itself. However, such mechanical buttons are susceptible toaging, wear, and tear that may reduce the useful life of a mobile deviceand/or may require significant repair if malfunction occurs. Also, thepresence of mechanical buttons may render it difficult to manufacturemobile devices that are waterproof. Accordingly, mobile devicemanufacturers are increasingly looking to equip mobile devices withvirtual buttons that act as a human-machine interface allowing forinteraction between a user of a mobile device and the mobile deviceitself. Similarly, mobile device manufacturers are increasingly lookingto equip mobile devices with other virtual interface areas (e.g., avirtual slider, interface areas of a body of the mobile device otherthan a touch screen, etc.). Ideally, for best user experience, suchvirtual interface areas should look and feel to a user as if amechanical button or other mechanical interface were present instead ofa virtual button or virtual interface area.

Presently, linear resonant actuators (LRAs) and other vibrationalactuators (e.g., rotational actuators, vibrating motors, etc.) areincreasingly being used in mobile devices to generate vibrationalfeedback in response to user interaction with human-machine interfacesof such devices. Typically, a sensor (traditionally a force or pressuresensor) detects user interaction with the device (e.g., a finger presson a virtual button of the device) and in response thereto, the linearresonant actuator may vibrate to provide feedback to the user. Forexample, a linear resonant actuator may vibrate in response to userinteraction with the human-machine interface to mimic to the user thefeel of a mechanical button click.

However, there is a need in the industry for sensors to detect userinteraction with a human-machine interface, wherein such sensors provideacceptable levels of sensor sensitivity, power consumption, and size.

SUMMARY

In accordance with the teachings of the present disclosure, thedisadvantages and problems associated with sensing of human-machineinterface interactions in a mobile device may be reduced or eliminated.

In accordance with embodiments of the present disclosure, a system mayinclude at least one resistive-inductive-capacitive sensor and a controlcircuit configured to maintain timing parameters for operation of the atleast one resistive-inductive-capacitive sensor and vary at least one ofthe timing parameters to control a spectrum associated with the at leastone resistive-inductive-capacitive sensor, wherein the spectrumcomprises one of a sensor activity spectrum of the at least oneresistive-inductive-capacitive sensor and a current usage spectrumassociated with electrical current delivered to the at least oneresistive-inductive-capacitive sensor from a source of electricalenergy.

In accordance with these and other embodiments of the presentdisclosure, a method may include maintaining timing parameters foroperation of the at least one resistive-inductive-capacitive sensor andvarying at least one of the timing parameters to control a spectrumassociated with the at least one resistive-inductive-capacitive sensor,wherein the spectrum comprises one of a sensor activity spectrum of theat least one resistive-inductive-capacitive sensor and a current usagespectrum associated with electrical current delivered to the at leastone resistive-inductive-capacitive sensor from a source of electricalenergy.

In accordance with these and other embodiments of the present disclosurea host device may include an enclosure, a resonant phase sensing systemintegral to the enclosure, and a control circuit. The resonant phasesensing system may include at least one resistive-inductive-capacitivesensor and a driver configured to drive the at least oneresistive-inductive-capacitive sensor with a driving signal at a drivingfrequency. The control circuit may configured to maintain timingparameters for operation of the at least oneresistive-inductive-capacitive sensor and vary at least one of thetiming parameters to control a spectrum associated with the at least oneresistive-inductive-capacitive sensor, wherein the spectrum comprisesone of a sensor activity spectrum of the at least oneresistive-inductive-capacitive sensor and a current usage spectrumassociated with electrical current delivered to the at least oneresistive-inductive-capacitive sensor from a source of electricalenergy.

Technical advantages of the present disclosure may be readily apparentto one having ordinary skill in the art from the figures, descriptionand claims included herein. The objects and advantages of theembodiments will be realized and achieved at least by the elements,features, and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description andthe following detailed description are examples and explanatory and arenot restrictive of the claims set forth in this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, in which like referencenumbers indicate like features, and wherein:

FIG. 1 illustrates a block diagram of selected components of an examplemobile device, in accordance with embodiments of the present disclosure;

FIG. 2 illustrates a mechanical member separated by a distance from aninductive coil, in accordance with embodiments of the presentdisclosure;

FIG. 3 illustrates selected components of a model for a mechanicalmember and inductive coil that may be used in an inductive sensingsystem, in accordance with embodiments of the present disclosure;

Each of FIGS. 4A-4C illustrates a diagram of selected components of anexample resonant phase sensing system, in accordance with embodiments ofthe present disclosure;

FIG. 5 illustrates a diagram of selected components of an exampleresonant phase sensing system implementing time-division multiplexedprocessing of multiple resistive-inductive-capacitive sensors, inaccordance with embodiments of the present disclosure;

FIG. 6 illustrates an example timing diagram depicting typicaltime-division multiplexed operation of resistive-inductive-capacitivesensors, in accordance with embodiments of the present disclosure;

FIG. 7 is an example timing diagram depicting a time-divisionmultiplexed operation of resistive-inductive-capacitive sensors in whichone or more of scan period duration, individual conversion times ofresistive-inductive-capacitive sensors, delays between conversion timesof resistive-inductive-capacitive sensors within a scan period, and/orthe activation sequence of resistive-inductive-capacitive sensors withina scan period may be varied, in accordance with embodiments of thepresent disclosure; and

FIG. 8 is an example timing diagram depicting a time-divisionmultiplexed operation of resistive-inductive-capacitive sensors withinwhich an unused timing slot may be present in a scan period, inaccordance with embodiments of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates a block diagram of selected components of an examplemobile device 102, in accordance with embodiments of the presentdisclosure. As shown in FIG. 1, mobile device 102 may comprise anenclosure 101, a controller 103, a memory 104, a mechanical member 105,a microphone 106, a linear resonant actuator 107, a radiotransmitter/receiver 108, a speaker 110, and a resonant phase sensingsystem 112.

Enclosure 101 may comprise any suitable housing, casing, or otherenclosure for housing the various components of mobile device 102.Enclosure 101 may be constructed from plastic, metal, and/or any othersuitable materials. In addition, enclosure 101 may be adapted (e.g.,sized and shaped) such that mobile device 102 is readily transported ona person of a user of mobile device 102. Accordingly, mobile device 102may include but is not limited to a smart phone, a tablet computingdevice, a handheld computing device, a personal digital assistant, anotebook computer, a video game controller, or any other device that maybe readily transported on a person of a user of mobile device 102.

Controller 103 may be housed within enclosure 101 and may include anysystem, device, or apparatus configured to interpret and/or executeprogram instructions and/or process data, and may include, withoutlimitation a microprocessor, microcontroller, digital signal processor(DSP), application specific integrated circuit (ASIC), or any otherdigital or analog circuitry configured to interpret and/or executeprogram instructions and/or process data. In some embodiments,controller 103 may interpret and/or execute program instructions and/orprocess data stored in memory 104 and/or other computer-readable mediaaccessible to controller 103.

Memory 104 may be housed within enclosure 101, may be communicativelycoupled to controller 103, and may include any system, device, orapparatus configured to retain program instructions and/or data for aperiod of time (e.g., computer-readable media). Memory 104 may includerandom access memory (RAM), electrically erasable programmable read-onlymemory (EEPROM), a Personal Computer Memory Card InternationalAssociation (PCMCIA) card, flash memory, magnetic storage, opto-magneticstorage, or any suitable selection and/or array of volatile ornon-volatile memory that retains data after power to mobile device 102is turned off.

Microphone 106 may be housed at least partially within enclosure 101,may be communicatively coupled to controller 103, and may comprise anysystem, device, or apparatus configured to convert sound incident atmicrophone 106 to an electrical signal that may be processed bycontroller 103, wherein such sound is converted to an electrical signalusing a diaphragm or membrane having an electrical capacitance thatvaries based on sonic vibrations received at the diaphragm or membrane.Microphone 106 may include an electrostatic microphone, a condensermicrophone, an electret microphone, a microelectromechanical systems(MEMs) microphone, or any other suitable capacitive microphone.

Radio transmitter/receiver 108 may be housed within enclosure 101, maybe communicatively coupled to controller 103, and may include anysystem, device, or apparatus configured to, with the aid of an antenna,generate and transmit radio-frequency signals as well as receiveradio-frequency signals and convert the information carried by suchreceived signals into a form usable by controller 103. Radiotransmitter/receiver 108 may be configured to transmit and/or receivevarious types of radio-frequency signals, including without limitation,cellular communications (e.g., 2G, 3G, 4G, LTE, etc.), short-rangewireless communications (e.g., BLUETOOTH), commercial radio signals,television signals, satellite radio signals (e.g., GPS), WirelessFidelity, etc.

A speaker 110 may be housed at least partially within enclosure 101 ormay be external to enclosure 101, may be communicatively coupled tocontroller 103, and may comprise any system, device, or apparatusconfigured to produce sound in response to electrical audio signalinput. In some embodiments, a speaker may comprise a dynamicloudspeaker, which employs a lightweight diaphragm mechanically coupledto a rigid frame via a flexible suspension that constrains a voice coilto move axially through a cylindrical magnetic gap. When an electricalsignal is applied to the voice coil, a magnetic field is created by theelectric current in the voice coil, making it a variable electromagnet.The voice coil and the driver's magnetic system interact, generating amechanical force that causes the voice coil (and thus, the attachedcone) to move back and forth, thereby reproducing sound under thecontrol of the applied electrical signal coming from the amplifier.

Mechanical member 105 may be housed within or upon enclosure 101, andmay include any suitable system, device, or apparatus configured suchthat all or a portion of mechanical member 105 displaces in positionresponsive to a force, a pressure, or a touch applied upon orproximately to mechanical member 105. In some embodiments, mechanicalmember 105 may be designed to appear as a mechanical button on theexterior of enclosure 101.

Linear resonant actuator 107 may be housed within enclosure 101, and mayinclude any suitable system, device, or apparatus for producing anoscillating mechanical force across a single axis. For example, in someembodiments, linear resonant actuator 107 may rely on an alternatingcurrent voltage to drive a voice coil pressed against a moving massconnected to a spring. When the voice coil is driven at the resonantfrequency of the spring, linear resonant actuator 107 may vibrate with aperceptible force. Thus, linear resonant actuator 107 may be useful inhaptic applications within a specific frequency range. While, for thepurposes of clarity and exposition, this disclosure is described inrelation to the use of linear resonant actuator 107, it is understoodthat any other type or types of vibrational actuators (e.g., eccentricrotating mass actuators) may be used in lieu of or in addition to linearresonant actuator 107. In addition, it is also understood that actuatorsarranged to produce an oscillating mechanical force across multiple axesmay be used in lieu of or in addition to linear resonant actuator 107.As described elsewhere in this disclosure, a linear resonant actuator107, based on a signal received from resonant phase sensing system 112,may render haptic feedback to a user of mobile device 102 for at leastone of mechanical button replacement and capacitive sensor feedback.

Together, mechanical member 105 and linear resonant actuator 107 mayform a human-interface device, such as a virtual interface (e.g., avirtual button), which, to a user of mobile device 102, has a look andfeel of a mechanical button or other mechanical interface of mobiledevice 102.

Resonant phase sensing system 112 may be housed within enclosure 101,may be communicatively coupled to mechanical member 105 and linearresonant actuator 107, and may include any system, device, or apparatusconfigured to detect a displacement of mechanical member 105 indicativeof a physical interaction (e.g., by a user of mobile device 102) withthe human-machine interface of mobile device 102 (e.g., a force appliedby a human finger to a virtual interface of mobile device 102). Asdescribed in greater detail below, resonant phase sensing system 112 maydetect displacement of mechanical member 105 by performing resonantphase sensing of a resistive-inductive-capacitive sensor for which animpedance (e.g., inductance, capacitance, and/or resistance) of theresistive-inductive-capacitive sensor changes in response todisplacement of mechanical member 105. Thus, mechanical member 105 maycomprise any suitable system, device, or apparatus which all or aportion thereof may displace, and such displacement may cause a changein an impedance of a resistive-inductive-capacitive sensor integral toresonant phase sensing system 112. Resonant phase sensing system 112 mayalso generate an electronic signal for driving linear resonant actuator107 in response to a physical interaction associated with ahuman-machine interface associated with mechanical member 105. Detail ofan example resonant phase sensing system 112 in accordance withembodiments of the present disclosure is depicted in greater detailbelow.

Although specific example components are depicted above in FIG. 1 asbeing integral to mobile device 102 (e.g., controller 103, memory 104,mechanical member 105, microphone 106, radio transmitter/receiver 108,speakers(s) 110, linear resonant actuator 107, etc.), a mobile device102 in accordance with this disclosure may comprise one or morecomponents not specifically enumerated above. For example, although FIG.1 depicts certain user interface components, mobile device 102 mayinclude one or more other user interface components in addition to thosedepicted in FIG. 1, including but not limited to a keypad, a touchscreen, and a display, thus allowing a user to interact with and/orotherwise manipulate mobile device 102 and its associated components. Inaddition, although FIG. 1 depicts only a single virtual buttoncomprising mechanical member 105 and linear resonant actuator 107 forpurposes of clarity and exposition, in some embodiments a mobile device102 may have multiple virtual interfaces, each comprising a respectivemechanical member 105 and linear resonant actuator 107.

Although, as stated above, resonant phase sensing system 112 may detectdisplacement of mechanical member 105 by performing resonant phasesensing of a resistive-inductive-capacitive sensor for which animpedance (e.g., inductance, capacitance, and/or resistance) of theresistive-inductive-capacitive sensor changes in response todisplacement of mechanical member 105, in some embodiments resonantphase sensing system 112 may primarily detect displacement of mechanicalmember 105 by using resonant phase sensing to determine a change in aninductance of a resistive-inductive-capacitive sensor. For example,FIGS. 2 and 3 illustrate selected components of an example inductivesensing application that may be implemented by resonant phase sensingsystem 112, in accordance with embodiments of the present disclosure.

Although the foregoing contemplates a resonant phase sensing system 112for use in a mobile device 102, the resonant phase sensing system 112may be used in any other suitable host device. A host device may includewithout limitation, a portable and/or battery-powered mobile computingdevice (e.g., a laptop, notebook, or tablet computer), a gaming console,a remote control device, a home automation controller, a domesticappliance (e.g., domestic temperature or lighting control system), atoy, a machine (e.g., a robot) such as a robot, an audio player, a videoplayer, and a mobile telephone (e.g., a smartphone).

FIG. 2 illustrates mechanical member 105 embodied as a metal plateseparated by a distance d from an inductive coil 202, in accordance withembodiments of the present disclosure. FIG. 3 illustrates selectedcomponents of a model for mechanical member 105 and inductive coil 202that may be used in an inductive sensing system 300, in accordance withembodiments of the present disclosure. As shown in FIG. 3, inductivesensing system 300 may include mechanical member 105, modeled as avariable electrical resistance 304 and a variable electrical inductance306, and may include inductive coil 202 in physical proximity tomechanical member 105 such that inductive coil 202 has a mutualinductance with mechanical member 105 defined by a variable couplingcoefficient k. As shown in FIG. 3, inductive coil 202 may be modeled asa variable electrical inductance 308 and a variable electricalresistance 310.

In operation, as a current I flows through inductive coil 202, suchcurrent may induce a magnetic field which in turn may induce an eddycurrent inside mechanical member 105. When a force is applied to and/orremoved from mechanical member 105, which alters distance d betweenmechanical member 105 and inductive coil 202, the coupling coefficientk, variable electrical resistance 304, and/or variable electricalinductance 306 may also change in response to the change in distance.These changes in the various electrical parameters may, in turn, modifyan effective impedance Z_(L) of inductive coil 202.

FIG. 4A illustrates a diagram of selected components of an exampleresonant phase sensing system 112A, in accordance with embodiments ofthe present disclosure. In some embodiments, resonant phase sensingsystem 112A may be used to implement resonant phase sensing system 112of FIG. 1. As shown FIG. 4A, resonant phase sensing system 112A mayinclude a resistive-inductive-capacitive sensor 402 and a processingintegrated circuit (IC) 412A.

As shown in FIG. 4A, resistive-inductive-capacitive sensor 402 mayinclude mechanical member 105, inductive coil 202, a resistor 404, andcapacitor 406, wherein mechanical member 105 and inductive coil 202 havea variable coupling coefficient k. Although shown in FIG. 4A to bearranged in parallel with one another, it is understood that inductivecoil 202, resistor 404, and capacitor 406 may be arranged in any othersuitable manner that allows resistive-inductive-capacitive sensor 402 toact as a resonant tank. For example, in some embodiments, inductive coil202, resistor 404, and capacitor 406 may be arranged in series with oneanother. In some embodiments, resistor 404 may not be implemented with astand-alone resistor, but may instead be implemented by a parasiticresistance of inductive coil 202, a parasitic resistance of capacitor406, and/or any other suitable parasitic resistance.

Processing IC 412A may be communicatively coupled toresistive-inductive-capacitive sensor 402 and may comprise any suitablesystem, device, or apparatus configured to implement a measurementcircuit to measure phase information associated withresistive-inductive-capacitive sensor 402 and based on the phaseinformation, determine a displacement of mechanical member 105 relativeto resistive-inductive-capacitive sensor 402. Thus, processing IC 412Amay be configured to determine an occurrence of a physical interaction(e.g., press or release of a virtual button) associated with ahuman-machine interface associated with mechanical member 105 based onthe phase information.

As shown in FIG. 4A, processing IC 412A may include a phase shifter 410,a voltage-to-current converter 408, a preamplifier 440, an intermediatefrequency mixer 442, a combiner 444, a programmable gain amplifier (PGA)414, a voltage-controlled oscillator (VCO) 416, a phase shifter 418, anamplitude and phase calculation block 431, a DSP 432, a low-pass filter434, and a combiner 450. Processing IC 412A may also include a coherentincident/quadrature detector implemented with an incident channelcomprising a mixer 420, a low-pass filter 424, and an analog-to-digitalconverter (ADC) 428, and a quadrature channel comprising a mixer 422, alow-pass filter 426, and an ADC 430 such that processing IC 412A isconfigured to measure the phase information using the coherentincident/quadrature detector.

Phase shifter 410 may include any system, device, or apparatusconfigured to detect an oscillation signal generated by processing IC412A (as explained in greater detail below) and phase shift suchoscillation signal (e.g., by 45 degrees) such that a normal operatingfrequency of resonant phase sensing system 112A, an incident componentof a sensor signal ϕ generated by pre-amplifier 440 is approximatelyequal to a quadrature component of sensor signal ϕ, so as to providecommon mode noise rejection by a phase detector implemented byprocessing IC 412A, as described in greater detail below.

Voltage-to-current converter 408 may receive the phase shiftedoscillation signal from phase shifter 410, which may be a voltagesignal, convert the voltage signal to a corresponding current signal,and drive the current signal on resistive-inductive-capacitive sensor402 at a driving frequency with the phase-shifted oscillation signal inorder to generate sensor signal ϕ which may be processed by processingIC 412A, as described in greater detail below. In some embodiments, adriving frequency of the phase-shifted oscillation signal may beselected based on a resonant frequency of resistive-inductive-capacitivesensor 402 (e.g., may be approximately equal to the resonant frequencyof resistive-inductive-capacitive sensor 402).

Preamplifier 440 may receive sensor signal ϕ) and condition sensorsignal ϕ) for frequency mixing, with mixer 442, to an intermediatefrequency Δf combined by combiner 444 with an oscillation frequencygenerated by VCO 416, as described in greater detail below, whereinintermediate frequency Δf is significantly less than the oscillationfrequency. In some embodiments, preamplifier 440, mixer 442, andcombiner 444 may not be present, in which case PGA 414 may receivesensor signal ϕ) directly from resistive-inductive-capacitive sensor402. However, when present, preamplifier 440, mixer 442, and combiner444 may allow for mixing sensor signal ϕ) down to a lower intermediatefrequency Δf which may allow for lower-bandwidth and more efficient ADCs(e.g., ADCs 428 and 430 of FIGS. 4A and 4B and ADC 429 of FIG. 4C,described below) and/or which may allow for minimization of phase and/orgain mismatches in the incident and quadrature paths of the phasedetector of processing IC 412A.

In operation, PGA 414 may further amplify sensor signal ϕ) to conditionsensor signal ϕ) for processing by the coherent incident/quadraturedetector. VCO 416 may generate an oscillation signal to be used as abasis for the signal driven by voltage-to-current converter 408, as wellas the oscillation signals used by mixers 420 and 422 to extractincident and quadrature components of amplified sensor signal ϕ). Asshown in FIG. 4A, mixer 420 of the incident channel may use an unshiftedversion of the oscillation signal generated by VCO 416, while mixer 422of the quadrature channel may use a 90-degree shifted version of theoscillation signal phase shifted by phase shifter 418. As mentionedabove, the oscillation frequency of the oscillation signal generated byVCO 416 may be selected based on a resonant frequency ofresistive-inductive-capacitive sensor 402 (e.g., may be approximatelyequal to the resonant frequency of resistive-inductive-capacitive sensor402).

In the incident channel, mixer 420 may extract the incident component ofamplified sensor signal ϕ), low-pass filter 424 may filter out theoscillation signal mixed with the amplified sensor signal ϕ) to generatea direct current (DC) incident component, and ADC 428 may convert suchDC incident component into an equivalent incident component digitalsignal for processing by amplitude and phase calculation block 431.Similarly, in the quadrature channel, mixer 422 may extract thequadrature component of amplified sensor signal ϕ, low-pass filter 426may filter out the phase-shifted oscillation signal mixed with theamplified sensor signal ϕ to generate a direct current (DC) quadraturecomponent, and ADC 430 may convert such DC quadrature component into anequivalent quadrature component digital signal for processing byamplitude and phase calculation block 431.

Amplitude and phase calculation block 431 may include any system,device, or apparatus configured to receive phase information comprisingthe incident component digital signal and the quadrature componentdigital signal and based thereon, extract amplitude and phaseinformation.

DSP 432 may include any system, device, or apparatus configured tointerpret and/or execute program instructions and/or process data. Inparticular, DSP 432 may receive the phase information and the amplitudeinformation generated by amplitude and phase calculation block 431 andbased thereon, determine a displacement of mechanical member 105relative to resistive-inductive-capacitive sensor 402, which may beindicative of an occurrence of a physical interaction (e.g., press orrelease of a virtual button or other interaction with a virtualinterface) associated with a human-machine interface associated withmechanical member 105 based on the phase information. DSP 432 may alsogenerate an output signal indicative of the displacement. In someembodiments, such output signal may comprise a control signal forcontrolling mechanical vibration of linear resonant actuator 107 inresponse to the displacement.

The phase information generated by amplitude and phase calculation block431 may be subtracted from a reference phase ϕ_(ref) by combiner 450 inorder to generate an error signal that may be received by low-passfilter 434. Low-pass filter 434 may low-pass filter the error signal,and such filtered error signal may be applied to VCO 416 to modify thefrequency of the oscillation signal generated by VCO 416, in order todrive sensor signal ϕ towards reference phase ϕ_(ref). As a result,sensor signal ϕ may comprise a transient decaying signal in response toa “press” of a virtual button (or other interaction with a virtualinterface) associated with resonant phase sensing system 112A as well asanother transient decaying signal in response to a subsequent “release”of the virtual button (or other interaction with a virtual interface).Accordingly, low-pass filter 434 in connection with VCO 416 mayimplement a feedback control loop that may track changes in operatingparameters of resonant phase sensing system 112A by modifying thedriving frequency of VCO 416.

FIG. 4B illustrates a diagram of selected components of an exampleresonant phase sensing system 112B, in accordance with embodiments ofthe present disclosure. In some embodiments, resonant phase sensingsystem 112B may be used to implement resonant phase sensing system 112of FIG. 1. Resonant phase sensing system 112B of FIG. 4B may be, in manyrespects, similar to resonant phase sensing system 112A of FIG. 4A.Accordingly, only those differences between resonant phase sensingsystem 112B and resonant phase sensing system 112A may be describedbelow. As shown in FIG. 4B, resonant phase sensing system 112B mayinclude processing IC 412B in lieu of processing IC 412A. Processing IC412B of FIG. 4B may be, in many respects, similar to processing IC 412Aof FIG. 4A. Accordingly, only those differences between processing IC412B and processing IC 412A may be described below.

Processing IC 412B may include fixed-frequency oscillator 417 andvariable phase shifter 419 in lieu of VCO 416 of processing IC 412A.Thus, in operation, oscillator 417 may drive a fixed driving signal andoscillation signal which variable phase shifter 419 may phase shift togenerate oscillation signals to be mixed by mixers 420 and 422. Similarto that of processing IC 412A, low-pass filter 434 may low-pass filteran error signal based on phase information extracted by amplitude andphase calculation block 431, but instead such filtered error signal maybe applied to variable phase shifter 419 to modify the phase offset ofthe oscillation signal generated by oscillator 417, in order to drivesensor signal ϕ towards indicating a phase shift of zero. As a result,sensor signal ϕ may comprise a transient decaying signal in response toa “press” of a virtual button (or other interaction with a virtualinterface) associated with resonant phase sensing system 112B as well asanother transient decaying signal in response to a subsequent “release”of the virtual button (or other interaction with a virtual interface).Accordingly, low-pass filter 434 in connection with variable phaseshifter 419 may implement a feedback control loop that may track changesin operating parameters of resonant phase sensing system 112B bymodifying the phase shift applied by variable phase shifter 419.

FIG. 4C illustrates a diagram of selected components of an exampleresonant phase sensing system 112C, in accordance with embodiments ofthe present disclosure. In some embodiments, resonant phase sensingsystem 112C may be used to implement resonant phase sensing system 112of FIG. 1. Resonant phase sensing system 112C of FIG. 4C may be, in manyrespects, similar to resonant phase sensing system 112A of FIG. 4A.Accordingly, only those differences between resonant phase sensingsystem 112C and resonant phase sensing system 112A may be describedbelow. For example, a particular difference between resonant phasesensing system 112C and resonant phase sensing system 112A is thatresonant phase sensing system 112C may include ADC 429 and ADC 431 inlieu of ADC 428 and ADC 430. Accordingly, a coherent incident/quadraturedetector for resonant phase sensing system 112C may be implemented withan incident channel comprising a digital mixer 421 and a digitallow-pass filter 425 (in lieu of analog mixer 420 and analog low-passfilter 424) and a quadrature channel comprising a digital mixer 423 anda low-pass filter 427 (in lieu of analog mixer 422 and analog low-passfilter 426) such that processing IC 412C is configured to measure thephase information using such coherent incident/quadrature detector.Although not explicitly shown, resonant phase sensing system 112B couldbe modified in a manner similar to that of how resonant phase sensingsystem 112A is shown to be modified to result in resonant phase sensingsystem 112C.

FIG. 5 illustrates a diagram of selected components of an exampleresonant phase sensing system 112D implementing time-divisionmultiplexed processing of multiple resistive-inductive-capacitivesensors 402 (e.g., resistive-inductive-capacitive sensors 402A-402Dshown in FIG. 5), in accordance with embodiments of the presentdisclosure. In some embodiments, resonant phase sensing system 112D maybe used to implement resonant phase sensing system 112 of FIG. 1.Resonant phase sensing system 112D of FIG. 5 may be, in many respects,similar to resonant phase sensing system 112A of FIG. 4A. Accordingly,only those differences between resonant phase sensing system 112D andresonant phase sensing system 112A may be described below. Inparticular, resonant phase sensing system 112D may include a pluralityof resistive-inductive-capacitive sensors 402 (e.g.,resistive-inductive-capacitive sensors 402A-402D shown in FIG. 5) inlieu of the single resistive-inductive-capacitive sensor 402 shown inFIG. 4A. In addition, resonant phase sensing system 112D may includemultiplexers 502 and 504, each of which may select an output signal froma plurality of input signals responsive to a control signal SELECT,which may be controlled by time-division multiplexing control circuitry552.

Although FIG. 5 depicts four resistive-inductive-capacitive sensors402A-402D for purposes of clarity and exposition, resonant phase sensingsystem 112D may include any suitable number ofresistive-inductive-capacitive sensors 402.

Control circuit 552 may comprise any suitable system, device, orapparatus configured to control time-division multiplexed sensing on oneor more resistive-inductive-capacitive sensors 402, as described ingreater detail below. Although FIG. 5 shows control circuitry 552 asbeing integral to processing IC 412D, in some embodiments controlcircuitry 552 may be implemented by controller 103 or another suitablecomponent of mobile device 102.

Accordingly, while in some embodiments a device such as mobile device102 may comprise a plurality of resistive-inductive-capacitive sensors402 which may be simultaneously driven and separately processed by arespective processing IC, in other embodiments a resonant phase sensingsystem (e.g., resonant phase sensing system 112D) may driveresistive-inductive-capacitive sensors 402 in a time-divisionmultiplexed manner Such approach may reduce power consumption and devicesize as compared with multiple-sensor implementations in which themultiple sensors are simultaneously driven and/or sensed. Device sizemay be reduced by time-division multiplexing multiple sensors into asingle driver and measurement circuit channel, wherein only a singledriver and a single measurement circuit may be required, thus minimizingan amount of integrated circuit area needed to perform driving andmeasurement. In addition, by leveraging a single driver and measurementcircuit, no calibration may be needed to adjust for mismatches and/orerrors between different drivers and/or different measurement circuits.

For purposes of clarity and exposition, preamplifier 440, mixer 442, andcombiner 444 have been excluded from FIG. 5. However, in someembodiments, processing IC 412D may include preamplifier 440, mixer 442,and combiner 444 similar to that depicted in FIGS. 4A-4C.

In resonant phase sensing system 112D, control circuitry 552 may providecontrol of control signal SELECT in order to, for a first duration of ascan period, select a first resistive-inductive-capacitive sensor (e.g.,resistive-inductive-capacitive sensor 402A) to be driven byvoltage-to-current converter 408 and measured by the measurement circuitimplemented by processing IC 412D. During such first duration, controlcircuitry 552 may place other resistive-inductive-capacitive sensors(e.g., resistive-inductive-capacitive sensors 402B, 402C, and 402D) in alow-impedance state. Similarly, during a second duration of the scanperiod, control circuitry 552 may provide control of control signalSELECT in order to select a second resistive-inductive-capacitive sensor(e.g., resistive-inductive-capacitive sensor 402B) to be driven byvoltage-to-current converter 408 and measured by the measurement circuitimplemented by processing IC 412D. During such second duration, controlcircuitry 552 may place other resistive-inductive-capacitive sensors(e.g., resistive-inductive-capacitive sensors 402A, 402C, 402D) in alow-impedance state. A similar process may allow for sensing otherresistive-inductive-capacitive sensors in other durations of the scanperiod. Such an approach may minimize power consumption withinunselected resistive-inductive-capacitive sensors 402.

To further illustrate, FIG. 6 is an example timing diagram depictingtypical time-division multiplexed operation ofresistive-inductive-capacitive sensors 402, in accordance withembodiments of the present disclosure. As shown in FIG. 6, during eachscan period of resonant phase sensing system 112D, at the beginning ofsuch scan period, control circuitry 552 may causeresistive-inductive-capacitive sensor 402A to become active for a firstconversion time period 602 (while resistive-inductive-capacitive sensors402B, 402C, and 402D remain inactive). After completion of the firstconversion time period, and during a second conversion time period 604,control circuitry 552 may cause resistive-inductive-capacitive sensor402B to become active (while resistive-inductive-capacitive sensors402A, 402C, and 402D remain inactive). After completion of the secondconversion time period, and during a third conversion time period 606,control circuitry 552 may cause resistive-inductive-capacitive sensor402C to become active (while resistive-inductive-capacitive sensors402A, 402B, and 402D remain inactive). After completion of the thirdconversion time period, and during a fourth conversion time period 608,control circuitry 552 may cause resistive-inductive-capacitive sensor402D to become active (while resistive-inductive-capacitive sensors402A, 402B, and 402C remain inactive). After the scan period has ended,a new scan period may begin and repeat the same process.

Although FIG. 6 depicts each scan period having four conversion times,in some embodiments, a scan period may have more or less conversiontimes, depending on, for example, a number ofresistive-inductive-capacitive sensors 402 present in resonant phasesensing system 112D.

In some embodiments, during a conversion time for aresistive-inductive-capacitive sensor 402, a driving signal delivered(e.g., from voltage-to-current converter 408) to suchresistive-inductive-capacitive sensor 402 may be increased from abeginning of the conversion time to a maximum drive strength anddecreased from the maximum drive strength until an end of the conversiontime.

Time-division multiplexing as shown in FIG. 6 may be useful for a numberof reasons, including reduced power consumption and/or reducing oreliminating parasitic coupling between neighboring sensors. Such powerconsumption may vary based on a number of factors, including withoutlimitation a scan rate and conversion time associated with thetime-division multiplexing. As scan rate increases (e.g., as more scansare performed within a given measure of time), power consumption mayincrease. Similarly, as conversion time increases, power consumption mayincrease as longer conversion times require circuits to remain activefor a longer duration of time.

Using the typical time-division multiplexed approach represented by FIG.6 in which conversion time and scan rate are at fixed frequencies, tonalpatterns may appear on a power supply and/or radiate from one or moreinductive coils 202 of the resistive-inductive-capacitive sensors 402.As such tonal patterns may negatively affect measurement, it may bedesirable to mitigate or eliminate such tonal patterns. Tonal patternsin operation of a particular sensor may increase the susceptibility ofthe sensor to electromagnetic interference at particular and relatedfrequencies to the tone, as well as potentially increasing theelectromagnetic interference which may be induced by the sensor stimulusat those frequencies to other components of mobile device 102. Tonalpatterns in power usage by the measurement system may likewise increasethe susceptibility to the power supply noise of the measurement system,as well as the power supply noise at the various tonal frequenciespresented to other devices operating from the same power supply.

To overcome these potential problems, control circuitry 552 may beconfigured to vary, from one scan period to the next, one or more of theduration of the scan period, individual conversion times ofresistive-inductive-capacitive sensors 402, delays between conversiontimes of resistive-inductive-capacitive sensors 402 within a scanperiod, and/or the activation sequence of resistive-inductive-capacitivesensors 402 within a scan period. For example, FIG. 7 is an exampletiming diagram depicting a time-division multiplexed operation ofresistive-inductive-capacitive sensors 402 in which one or more of scanperiod duration, individual conversion times ofresistive-inductive-capacitive sensors 402, delays between conversiontimes of resistive-inductive-capacitive sensors 402 within a scanperiod, and/or the activation sequence of resistive-inductive-capacitivesensors 402 within a scan period may be varied, in accordance withembodiments of the present disclosure.

As shown in FIG. 7, control circuitry 552 may control time-divisionmultiplexing of processing IC 412D to vary a conversion time for eachresistive-inductive-capacitive sensor 402, such that differentresistive-inductive-capacitive sensors 402 may have different respectiveconversion times within a scan period and/or such that the sameresistive-inductive-capacitive sensor 402 may have different conversiontimes between scan periods. For example, as depicted in FIG. 7,resistive-inductive-capacitive sensor 402A may have a conversion time ofT_(c1), resistive-inductive-capacitive sensor 402B may have a conversiontime of T_(c2), resistive-inductive-capacitive sensor 402A may have aconversion time of T_(c3), and resistive-inductive-capacitive sensor402A may have a conversion time of T_(c4).

Also as shown in FIG. 7, control circuitry 552 may control time-divisionmultiplexing of processing IC 412D to vary a delay between therespective conversion times within a scan period, wherein such delaysmay be different within a scan period, and an individual delay may varyfrom scan period to scan period. For example, a delay T_(d12) may bepresent between conversion time T_(c1) and conversion time T_(c2), adelay T_(d23) may be present between conversion time T_(c2) andconversion time t_(c3), and a delay t_(d34) may be present betweenconversion time T_(c3) and conversion time T_(c4).

Also as shown in FIG. 7, control circuitry 552 may control time-divisionmultiplexing of processing IC 412D to vary, from scan period to scanperiod, an activation sequence of resistive-inductive-capacitive sensors402 within respective scan periods. For example, during a scan period N,control circuitry 552 may cause an activation sequence ofresistive-inductive-capacitive sensor 402A, thenresistive-inductive-capacitive sensor 402B, thenresistive-inductive-capacitive sensor 402C, thenresistive-inductive-capacitive sensor 402D, and on a subsequent scanperiod N+1, may cause an activation sequence ofresistive-inductive-capacitive sensor 402A, thenresistive-inductive-capacitive sensor 402C, thenresistive-inductive-capacitive sensor 402B, thenresistive-inductive-capacitive sensor 402D.

Although not explicitly depicted in FIG. 7, control circuitry 552 maycontrol time-division multiplexing of processing IC 412D to vary thedurations of individual scan periods. For example, scan period N mayhave a duration of T_(s1) while scan period N+1 may have a duration ofT_(s2), wherein T_(s1) and T_(s2), may or may not be equal in duration.For example, FIG. 8 is an example timing diagram depicting atime-division multiplexed operation of resistive-inductive-capacitivesensors 402 in which an unused timing slot may be present in a scanperiod, in accordance with embodiments of the present disclosure. Suchunused slot within a scan period may define a period of time within suchscan period that no resistive-inductive-capacitive sensor 402 is active.Further, the position of such unused slot may vary from scan period toscan period, as shown in FIG. 8.

In instances in which a scan period or conversion time is varied,control circuitry 552 may be configured to vary such duration in amanner to result in a desired average, mean, or median of such durationover time.

Control circuitry 552 may be configured to determine the various scanperiods, conversion times, activation sequences, delays, and/or unusedslot positions in any suitable manner, including use of a random number,a pseudo-random number generated using a linear-feedback shift register,and/or use of a defined repeating pattern.

Benefits of varying scan periods, conversion times, delays, activationsequences, and unused slot positions may include spreading of a spectrumof energy in multiple individual resistive-capacitive-inductive sensorsand/or spreading of a spectrum of a current draw of processing IC 412D.In other words, the scan periods, conversion times, delays, activationsequences, and unused slot positions may comprise timing parameters forthe operation of one or more resistive-capacitive-inductive sensors andvarying of the scan periods, conversion times, delays, activationsequences, and unused slot positions may be effective to control asensor activity spectrum of the one or moreresistive-capacitive-inductive sensors and/or a current usage spectrumassociated with the one or more resistive-capacitive-inductive sensors.

A similar approach to that shown in FIG. 8 may also be used in aresonant phase sensing system having only a singleresistive-inductive-capacitive sensor 402 in order to reduce powerconsumption associated with such sensor. For example, instead oftime-division multiplexing among multiple sensors, a singleresistive-inductive-capacitive sensor 402 may be duty-cycled inoperation such that, for a first portion of a cycle of a measurementcircuit (e.g., processing IC 412A), the measurement circuit may operatein a low power mode, and, for a second portion of the cycle of themeasurement circuit, the measurement circuit may operate in a high powermode in which the measurement circuit consumes more power than in thelow power mode, and wherein the measurement circuit performs measurementof the phase information and determination of the displacement of amechanical member (e.g., mechanical member 105) during the secondportion. Another way to illustrate this approach is to consider ascenario in which only one resistive-inductive-capacitive sensor 402conversion time is present in FIG. 8, along with an unused slot, in eachscan period.

Although not explicitly shown, resonant phase sensing system 112B couldbe modified in a manner similar to that of how resonant phase sensingsystem 112A is shown to be modified to result in resonant phase sensingsystem 112D, such that resonant phase sensing system 112B couldimplement time-division multiplexed sensing on a plurality ofresistive-inductive-capacitive sensors 402. Similarly, although notexplicitly shown, resonant phase sensing system 112C could be modifiedin a manner similar to that of how resonant phase sensing system 112A isshown to be modified to result in resonant phase sensing system 112D,such that resonant phase sensing system 112C could implementtime-division multiplexed sensing on a plurality ofresistive-inductive-capacitive sensors 402.

Although the foregoing contemplates use of closed-loop feedback forsensing of displacement, the various embodiments represented by FIGS.4A-8 may be modified to implement an open-loop system for sensing ofdisplacement. In such an open-loop system, a processing IC may includeno feedback path from amplitude and phase calculation block 431 to VCO416 or variable phase shifter 419 and thus may also lack a feedbacklow-pass filter 434. Thus, a phase measurement may still be made bycomparing a change in phase to a reference phase value, but theoscillation frequency driven by VCO 416 may not be modified or the phaseshifted by variable phase shifter 419 may not be shifted.

Although the foregoing contemplates use of a coherentincident/quadrature detector as a phase detector for determining phaseinformation associated with resistive-inductive-capacitive sensor 402, aresonant phase sensing system 112 may perform phase detection and/orotherwise determine phase information associated withresistive-inductive-capacitive sensor 402 in any suitable manner,including, without limitation, using only one of the incident path orquadrature path to determine phase information.

In some embodiments, an incident/quadrature detector as disclosed hereinmay include one or more frequency translation stages that translate thesensor signal into direct-current signal directly or into anintermediate frequency signal and then into a direct-current signal. Anyof such frequency translation stages may be implemented either digitallyafter an analog-to-digital converter stage or in analog before ananalog-to-digital converter stage.

Although the foregoing contemplates use of a coherentincident/quadrature detector as a phase detector for determining phaseinformation associated with a resistive-inductive-capacitive sensor 402,in some embodiments, changes in a resistive-inductive-capacitive sensor402 may be measured by operating such resistive-inductive-capacitivesensor 402 as an oscillator and measuring its frequency of oscillationand changes thereto.

In addition, although the foregoing contemplates measuring changes inresistance and inductance in resistive-inductive-capacitive sensor 402caused by displacement of mechanical member 105, other embodiments mayoperate based on a principle that any change in impedance based ondisplacement of mechanical member 105 may be used to sense displacement.For example, in some embodiments, displacement of mechanical member 105may cause a change in a capacitance of resistive-inductive-capacitivesensor 402, such as if mechanical member 105 included a metal plateimplementing one of the capacitive plates of capacitor 406.

Although DSP 432 may be capable of processing phase information to makea binary determination of whether physical interaction associated with ahuman-machine interface associated with mechanical member 105 hasoccurred and/or ceased to occur, in some embodiments, DSP 432 mayquantify a duration of a displacement of mechanical member 105 to morethan one detection threshold, for example to detect different types ofphysical interactions (e.g., a short press of a virtual button versus along press of the virtual button). In these and other embodiments, DSP432 may quantify a magnitude of the displacement to more than onedetection threshold, for example to detect different types of physicalinteractions (e.g., a light press of a virtual button versus a quick andhard press of the virtual button).

As used herein, when two or more elements are referred to as “coupled”to one another, such term indicates that such two or more elements arein electronic communication or mechanical communication, as applicable,whether connected indirectly or directly, with or without interveningelements.

This disclosure encompasses all changes, substitutions, variations,alterations, and modifications to the example embodiments herein that aperson having ordinary skill in the art would comprehend. Similarly,where appropriate, the appended claims encompass all changes,substitutions, variations, alterations, and modifications to the exampleembodiments herein that a person having ordinary skill in the art wouldcomprehend. Moreover, reference in the appended claims to an apparatusor system or a component of an apparatus or system being adapted to,arranged to, capable of, configured to, enabled to, operable to, oroperative to perform a particular function encompasses that apparatus,system, or component, whether or not it or that particular function isactivated, turned on, or unlocked, as long as that apparatus, system, orcomponent is so adapted, arranged, capable, configured, enabled,operable, or operative. Accordingly, modifications, additions, oromissions may be made to the systems, apparatuses, and methods describedherein without departing from the scope of the disclosure. For example,the components of the systems and apparatuses may be integrated orseparated. Moreover, the operations of the systems and apparatusesdisclosed herein may be performed by more, fewer, or other componentsand the methods described may include more, fewer, or other steps.Additionally, steps may be performed in any suitable order. As used inthis document, “each” refers to each member of a set or each member of asubset of a set.

Although exemplary embodiments are illustrated in the figures anddescribed below, the principles of the present disclosure may beimplemented using any number of techniques, whether currently known ornot. The present disclosure should in no way be limited to the exemplaryimplementations and techniques illustrated in the drawings and describedabove.

Unless otherwise specifically noted, articles depicted in the drawingsare not necessarily drawn to scale.

All examples and conditional language recited herein are intended forpedagogical objects to aid the reader in understanding the disclosureand the concepts contributed by the inventor to furthering the art, andare construed as being without limitation to such specifically recitedexamples and conditions. Although embodiments of the present disclosurehave been described in detail, it should be understood that variouschanges, substitutions, and alterations could be made hereto withoutdeparting from the spirit and scope of the disclosure.

Although specific advantages have been enumerated above, variousembodiments may include some, none, or all of the enumerated advantages.Additionally, other technical advantages may become readily apparent toone of ordinary skill in the art after review of the foregoing figuresand description.

To aid the Patent Office and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims or claimelements to invoke 35 U.S.C. § 112(f) unless the words “means for” or“step for” are explicitly used in the particular claim.

What is claimed is:
 1. A system comprising: at least oneresistive-inductive-capacitive sensor; and a control circuit configuredto: maintain timing parameters for operation of the at least oneresistive-inductive-capacitive sensor; and vary at least one of thetiming parameters to control a spectrum associated with the at least oneresistive-inductive-capacitive sensor, wherein the spectrum comprisesone of a sensor activity spectrum of the at least oneresistive-inductive-capacitive sensor and a current usage spectrumassociated with electrical current delivered to the at least oneresistive-inductive-capacitive sensor from a source of electricalenergy.
 2. The system of claim 1, wherein the timing parameters compriseat least one of: an order in which the at least oneresistive-inductive-capacitive sensor is scanned during a scan period; atime between successive observations of tworesistive-inductive-capacitive sensors of the at least oneresistive-inductive-capacitive sensor; a time between successiveobservations of particular resistive-inductive-capacitive sensors; and aduration within the scan period for observing a particularresistive-inductive-capacitive sensor of the at least oneresistive-inductive-capacitive sensor.
 3. The system of claim 1, whereinwithin the duration within the scan period for observing a particularresistive-inductive-capacitive sensor of the at least oneresistive-inductive-capacitive sensor, a driving signal for driving theat least one resistive-inductive-capacitive sensor is increased from abeginning of the duration to a maximum drive strength and decreased fromthe maximum drive strength until an end of the duration.
 4. The systemof claim 1, wherein the control circuit is configured to randomly varyat least one of the timing parameters.
 5. The system of claim 1, whereinthe control circuit is configured to pseudo-randomly vary at least oneof the timing parameters.
 6. The system of claim 1, wherein the controlcircuit is configured to pseudo-randomly vary at least one of the timingparameters using a linear-feedback shift register.
 7. The system ofclaim 1, wherein the control circuit is configured to vary at least oneof the timing parameters in accordance with a fixed repeating pattern.8. The system of claim 1, wherein the timing parameters comprise atleast one of a presence, duration, and position of an unused slot inwhich none of the at least one resistive-inductive-capacitive sensors isactive.
 9. The system of claim 1, further comprising: a driverconfigured to drive the at least one resistive-inductive-capacitivesensor at a driving frequency; a measurement circuit communicativelycoupled to the at least one resistive-inductive-capacitive sensor andconfigured to: measure phase information associated with the at leastone resistive-inductive-capacitive sensor; and based on the phaseinformation, determine a displacement of a mechanical member relative tothe at least one resistive-inductive-capacitive sensor, wherein thedisplacement of the mechanical member causes a change in an impedance ofthe at least one resistive-inductive-capacitive sensor.
 10. The systemof claim 9, wherein the at least one resistive-inductive-capacitivesensor comprises a plurality of resistive-inductive-capacitive sensors,and the control circuit is configured to maintain the timing parametersin order to: time-division multiplex drive the plurality ofresistive-inductive-capacitive sensors; and time-division multiplexmeasure by the measurement circuit the phase information associated witheach of the plurality of resistive-inductive-capacitive sensors.
 11. Amethod comprising maintaining timing parameters for operation of the atleast one resistive-inductive-capacitive sensor; and varying at leastone of the timing parameters to control a spectrum associated with theat least one resistive-inductive-capacitive sensor, wherein the spectrumcomprises one of a sensor activity spectrum of the at least oneresistive-inductive-capacitive sensor and a current usage spectrumassociated with electrical current delivered to the at least oneresistive-inductive-capacitive sensor from a source of electricalenergy.
 12. The method of claim 11, wherein the timing parameterscomprise at least one of: an order in which the at least oneresistive-inductive-capacitive sensor is scanned during a scan period; atime between successive observations of tworesistive-inductive-capacitive sensors of the at least oneresistive-inductive-capacitive sensor; a time between successiveobservations of particular resistive-inductive-capacitive sensors; and aduration within the scan period for observing a particularresistive-inductive-capacitive sensor of the at least oneresistive-inductive-capacitive sensor.
 13. The method of claim 11,wherein within the duration within the scan period for observing aparticular resistive-inductive-capacitive sensor of the at least oneresistive-inductive-capacitive sensor, a driving signal for driving theat least one resistive-inductive-capacitive sensor is increased from abeginning of the duration to a maximum drive strength and decreased fromthe maximum drive strength until an end of the duration.
 14. The methodof claim 11, further comprising randomly varying at least one of thetiming parameters.
 15. The method of claim 11, further comprisingpseudo-randomly varying at least one of the timing parameters.
 16. Themethod of claim 11, further comprising pseudo-randomly varying at leastone of the timing parameters using a linear-feedback shift register. 17.The method of claim 11, further comprising varying at least one of thetiming parameters in accordance with a fixed repeating pattern.
 18. Themethod of claim 11, wherein the timing parameters comprise at least oneof a presence, duration, and position of an unused slot in which none ofthe at least one resistive-inductive-capacitive sensors is active. 19.The method of claim 11, further comprising: driving the at least oneresistive-inductive-capacitive sensor at a driving frequency; measuringphase information associated with the at least oneresistive-inductive-capacitive sensor; and based on the phaseinformation, determining a displacement of a mechanical member relativeto the at least one resistive-inductive-capacitive sensor, wherein thedisplacement of the mechanical member causes a change in an impedance ofthe at least one resistive-inductive-capacitive sensor.
 20. The methodof claim 19, wherein the at least one resistive-inductive-capacitivesensor comprises a plurality of resistive-inductive-capacitive sensors,and the method further comprises maintaining the timing parameters inorder to: time-division multiplex drive the plurality ofresistive-inductive-capacitive sensors; and time-division multiplexmeasure by the measurement circuit the phase information associated witheach of the plurality of resistive-inductive-capacitive sensors.
 21. Ahost device comprising: an enclosure; and a resonant phase sensingsystem integral to the enclosure and comprising: at least oneresistive-inductive-capacitive sensor; and a driver configured to drivethe at least one resistive-inductive-capacitive sensor with a drivingsignal at a driving frequency; and a control circuit configured to:maintain timing parameters for operation of the at least oneresistive-inductive-capacitive sensor; and vary at least one of thetiming parameters to control a spectrum associated with the at least oneresistive-inductive-capacitive sensor, wherein the spectrum comprisesone of a sensor activity spectrum of the at least oneresistive-inductive-capacitive sensor and a current usage spectrumassociated with electrical current delivered to the at least oneresistive-inductive-capacitive sensor from a source of electricalenergy.